Carburetor



Feb. '4, 1936. w; MARKWART 2,029,666

CARBURETOR Filed Feb. 9, 1933 2 Sheets-Sheet 1 Feb. 4, 1936. A w. MARKWART 2,029,666

CARBURETOR I Filed Feb. 9, 1955 2 Sheets-Sheet 2 Patented Feb. 4, 1936 CARBURET'OR Walter Markwart, Chemnitz/Niederwiesa, Germany, assignor to Marklin Apparatebau Gesellscha ft'mit beschrankter Haftung, Chemnitz, c Germany, acorporation of Germany Application February 9, 1933, Serial No. 656,011

- In Germany May 25, 1932.

6 Claims. (Cl. 261-62) The invention relates 'to a jet carburetor in which a preliminary mixture is fed by way of an atomizing chamber to the induction channel and an over-rich mixture is formed in the atomlzing tro'dnced' her from be low against an a her. in manner no tion of the entire ca also r ndered pcssioie lor the important component parts of the apparatus to be dismounted and insp cted at any The eci'ied drawings show two typical embodiinents oi the subject oi the invention in iongitudinal section.

Fig. l shows a carburetor according to the invention without provision for the supply of checking air,

chamber by means of an air nozzle pipe connected with the outer air.

It is already known to provide an extension of the atomizing chamber extending below the level oi the fuel, by which it becomes possible for the fuel which is not atomized in the atomizing chamber to be returned by outlets for atomization. The invention consists in a particularly advantageous construction of the carburetor in which the air nozzle pipe is disposed concentrically around the jet tube and is surrounded by a further concentric casing which is connected at the bottom (for instance by holes) with the extension oi the atomizing chamber.

it the carburetor operates with an auxiliary air admission for checking the negative pressure at the nozzle of the jet tube, the necessary for this purpose may likewise be disposed concern trically to the jet and b i space between thejet tube all t .asdngs disposed around in-the f concentric t bular members, ti

Fig. i2v shows a form of construction with provision for the supply of checking air. W in the carburetor according to Fig. 1, the de livery pipe 0 forming the end of the atomizing chamber i projects into the induction channel m. This delivery pipe on the side remote from the entering current of suction air is provided with the openings 10.. The delivery pipe is enclosed by the throttle valveq which, by means of the rod, 1', can be adjusted according to the desired conditions of operation.

Theactual atomizing chamber 2 extends into the attachment s otthe induction channel casing m. This attachment is bored out cylindrically and provided at the bottom with a screwthread 3?. Into this thread is screwed the actual air nozzle pipe Into a bore of the air nozzle pipe f there is introduced the jet tube a in 'such a manner that between the casing of the jet tube extension between the casing h and the or,

can be screwed out from below.

and the casing ,f of the air nozzle pipe there re- -mains a free annular space to which air can be fed by the ducts g which communicate with the atmosphere.

Over the air nozzle pipe 1 is placed the cylin drical casing it provided at the bottom with openings 7a through which the unatomized fuel which collects in the bottom of the atomizing chamber 1'. can return into the annular space benozzle pipe bore which latter is closed by a plug y. This space a: is connected with the passage 2 20 by the arm a leading to the float chamber.

' The described arrangement operates as follows: In consequence of the current of air acting in the induction channel m, :Euel mixture is sucked from the atomizing chamber 2' through theholes p of the delivery pipe 0. The fuel mixture is formed by the fuel flowing from the space :0

through the calibrated plug and the jet tube a "d which mixed at the exit of the tube th the outer flowing from the .ular oi the air nozzle pipe i. i'his prel l'llilt ing is assisted by the deflection which occurs thelupper end of the casing h and p icularly' by the striking against the atomizing c Any unatomized particles of fuel carried along with the fuel mixture, run along the cute" face the casing it and arrive in the ch;

The upwardly flowing a ill at oi attachment s. annu space it passes over the upper the annular ducts it between the casin s a v and by the negative pressure produced the returned unatcmized fuel through the holes is from the chamber extension between the casing in and. the cylindrical attachment 8 and mixes it with the fuel coming from the calibrated plug c.

From Fig. l'it can e seenthat the casing it rests on shoulder oi"; the air nozzle pipe and together with'the air nozzle pipe and the jet tube a screw-ed into the boringof the air nozzle pipe Thus all the most important parts of the carburetor are united to one member which can easily be dismounted and examined.

In the carburetor operated with checking air according to Fig. 2, a is the jet tube and f the air nozzle pipe over which the casing h which is comically shaped at the top is placed. This casing is also provided with the openings k at the bottom, through which the non-atomized fuel 2 aoaaocc from the extension of the atomizing chamber i 4 can fiow back for atomization.

Between the jet tube a and the air nozzle pipe ,1

there is arranged a concentric sleeve 12. The an- 5 nular space left between the sleeve b and the jet tube a is connected at its upper end with the outer air and throughout its length, by the openings c, with the interior of the jet tube a. The checking air is supplied to the annular space between the jet tube a and the sleeve b, by an annular duct 6, which duct is'closed tmthe air nozzle pipe I by a casing d. The carbureting air is admitted throughwthe port g. The jet tube a is a 4 separate element from the casing d and can be removed by unscrewing from the base 1.

The fuel'in the jet tube a and also in the annular space between the jet tube a and' theqsleeve b is at the same level as that oi-the fuel in the float chamber S as indicated in the drawings by the chain line. When negative pressure prevails in the atomizing chamber i after the throttle valve tube a whereby a pre-mixing and preliminary atomization of the fuel takes place and to a certain extent a fuel foam is formed. The function of the checking air can be seen 35 from the following:-

The negative pressure in the jet tube a sucks the fuel through the calibrated plugn. The air of atmospheric pressure which enters through the holes 0 weakens the negative pressure at the 40 nozzle and thereby reduces the quantity of fuel supplied by it. The result is that when the thrct- .tle valve q is opened and when the fuel located in the jet tube a and the surrounding annular space is sucked up, the holes 0 are gradually freed 45 and when the throttle is opened the amount supplied by the main no e is checked. with progressive opening of the throttle valve without the checking air the mixture would become too rich, which assumption is based onthe laws govern- 50 ing the outflow of liquids.

If the throttle valve is more or less closed, the fuel rises in the annular space between the jet tube a and the casing'b, and collects here for the subsequent opening of the throttle, The already 55 preliminarily atomized fuel issuing from the jet tube a is further mixed with the air flowing from the air nozzle pipe I and passes by way of the chocked opening of the casing it into the atomi zing chamber i and through the holes p into the induction channel m. The delivery pipe 0 which projects into the induction chamber m preferably opens to the atomizing chamber in such a manner that theinternal diameter of the delivery pipe is greater than the diameter of the opening at the upper conically shaped end of the ca s-.

ing it surrounding thejet tube and the. air nozzle pipe. If the sum of all the openings p in the delivery pipe-o is sumciently great, the preliminary mixture of fuel and as which is accumulated in the atomizing chamber i can arrivein the induction-channel 1;: without throttling.

Iclaim:-

1. In a carburetor the combination of an induction channel, a mixture delivery pipe provided with holes opening into the induction channel, an atomizing chamber in connection with 5 the open end of the delivery pipe, a float chamber communicating with the atomizing chamber through a calibrated orifice, an atomizing jet tube adapted to receive fuel from the float chamber through said calibrated orifice and dis- 1o cha ing the fuel in said atomizing chamber, an air nozzle pipe disposed concentrically around the jet tube, and a concentric casing surrounding the air nozzle pipe and having openings at its lower end connecting the bottom of the atomiz- 15 ing chamber with the annular space between the casing and the air nozzle pipe, said casing terminating at its upper end in a conical member.

2. A carburetor as claimed in claim 1, in which the orifices of the mixture delivery pipe have such 20 a cross-sectional area that the jet of the fuel and air when issuing from the jet tube and the air nozzle pipe may pass without throttling into the delivery pipe.

3. In a carburetor as claimed in claim 1 ctge arrangement that the internal diameter of e delivery pipe is greater than that of the opening at the upper conically shaped end of the outer casing surrounding the jet tube and the air nozzle Pipe.

4. In a carburetoras claimed in claim 1 the arrangement that the casing disposed around the jet tube is in the form of concentric tubular members, the lower flanges of which rest on one another stepwise and are pressed by a plug sealing the bottom of the atomizing chamber, against an abutment on the atomizing chamber..

5. In a carburetor as claimed in claim 1, means for checking the negative pressure at the end of the jet tube, comprising a concentric sleeve between the jet tube and the -air nozzle pipe forming an annular space between'said sleeve and the jet tube and which is connected at the upper end with the outer air and over its length by openingswith the interior of the jet tube, and in which the casing and the sleeve disposed around the jet tube are in the form of concentric tubular members, the lower flanges of which rest on one another step-wise and are pressed by a closure sealing the bottom' of theatomizing chamber against an abutment on said chamber.

6. In a carburetor the combination of an induction channel, a mixture delivery pipe provided with holes openinginto the induction channel and having an'atomizing chamber therein, a float chamber communicating with the atomizing chamber through a calibrated orifice, an atomizing jet tube adapted to receive fuel from the float chamber through said calibrated orifice and discharging the fuel in saidatomizing chamber, 69 an air nozzle pipe disposed concentrically around the jet tube, and a concentric casing surround ing the air nozzle pipe and having openings at its lower end connecting the bottom of the atomizing chamber with the annular space between the casing and the air nozzle pipe, said casing terminating at its upper end in an apertured conical member extending over the end of the let tube.

' ,WALTER MARKWART. 

